Development of Sex Markers for Rockfishes, Sebastes, inhabiting the Northeast Pacific Ocean

Rockfishes (Sebastes) are important species for commercial and recreational fishing, as well as evolutionary and ecological research. It can be impractical to identify the sex of rockfishes using visual identification or lethal dissection, and the sex-determination systems of these species have not been studied extensively. The aim of this research was to investigate a potential genetic sex marker among eight species of rockfish from the Northeast Pacific Ocean using a Polymerase Chain Reaction Restriction Fragment Length Polymorphism (PCR-RFLP) assay. Sequencing was conducted to compare the location of the MluCI enzyme restriction site among two positive controls (gopher and black-and-yellow rockfishes) and six other rockfish species: black, blue, canary, deacon, widow, and yellowtail rockfishes. DNA sequencing revealed that MluCI restriction site location was not sex dependent, but instead species dependent. In three species, black, deacon, and yellowtail, PCR products amplified from both males and females contained the restriction site, whereas in other three other species, canary, blue, and widow, the restriction site was absent. Out of eight species, only one positive control, gopher rockfish, could be consistently and accurately sexed with the assay, where the MluCI cut site was male-specific. The second control, black-and-yellow rockfish, produced inconsistent results because the MluCI cut site was not sex dependent. Further sequencing is required to identify alternative restriction sites within the amplified PCR product. This nonlethal technique of sexing rockfish has the potential to enhance future research and the management and conservation of rockfishes.